In medieval times, some people kept a human skull in their home to remind themselves of mortality, and to view their priorities against the big picture of life and death. A modern equivalent is the dinosaur fossil. The fossilized remains of a once great and dominant species reminds the human species of our eventual choice: survival or extinction, or as Sagan put it, “spaceflight or extinction”.

It's a quick and interesting read and a great launch point for discussing our future in space. Thanks, Alex.